Grinding-mill.



H, L. DOHERTY.

GRINDING MILL.

APPLICATION FILED ocr.29.1909.

1,176,040. Patented Mar. 21,1916.

g lttmcaqcaz Henry Duh erTy, {Jvwawlfoz 7 -/ifl- 51 31 15 aftom uzxHENRY L. DOHERTY, OF NEW YORK, N. V

GRINDING-M ILL.

Specification of Letters Patent.

Patented Mar. 21, 1916.

Application filed October 29, 1909. Serial No. 525,386.

T 0 all whom it may concern Be it known that I, HENRY L. DOHERTY, acitizen of the United States, and resident of New York city, in thecounty of New York and State of New York, have invented certain new anduseful Improvements in a Grinding-Mill, of which the following is aspecification.

This invention relates to grinding mills and particularly to that kindof such mills commonly known as ball mills, in which the material isground in a rotating cylindrical barrel containing balls or pebbles.

The object of my invention is to prov de an improved form of such millsin which latter the reduction of the material is performed by a rollingand crushing action of the balls rather than by the grinding actionwhich accomplishes a large part of the reduction of the material in thecommonly used types of ball mills.

Other important objects of my invention are the prevention of theexcessive wear on the balls themselves due to their mutual grindingaction such as they have in the ordinary type of ball mill, and theelimination of the necessity for screens in the mill itself.

To this end my invention comprises a rotatable grinding barrel havinggrooves whose diametral planes are at right angles to the axis of thebarrel, grinding balls in each of said grooves, means for transferringmaterial that has passed under one ball to the groove of the next ball,the material being introduced into that portion of said groove which isat the moment on the descending side of the grinding barrel, means forrotating the barrel, means for introducing the material to be groundinto the grinding barrel and for Withdrawing the ground material fromthe barrel, as well as other features which arev fully set forth below.

In the accompanying drawing Figure 1 is a longitudinal section of myinvention taken on a vertical plane through the line A B of Fig. 2. Fig.2 is a cross-section of the mill on the line C D of Fig. 1 lookingtoward the discharge end of the mill. Fig. 3 is a partial longitudinalsection on A B of the discharge end of the mill looking in the oppositedirection to the view in Fig. 1. Fig. 4 is an elevation of the dischargeend of the mill. Fig. 5 is a side elevation of one of the grooved,segmental blocks of which the lining is constructed, showing a ballresting in the groove. Fig. 6 is a cross-section of the same. Fig. 7 isa part elevation of the charging end of the mill showing the location ofthe feed chute, etc.

In the drawings, 1 is the grinding barrel or drum, 2 the adjustablefixed shaft of the same, 3, the lining of thedrum which is divided intoa series of grooves, 4, 4, 4, etc. In the preferred construction of myinvention the lining is made of segmental blocks 5, of hard burned orvitrified clay having grooves, 4 and curved faces to fit the innersurface of the steel shell 7 of the grinding barrel.

8 and 8 are roller bearings supporting the drum 1.

9 is a driving device, preferably a motordriven shaft 10, carrying aspur wheel 11, gearing with a circular rack 12, carried by the shell 7of the drum 1.

13, is the feeding device which may be of any preferred type. as hereshown, being a helical conveyor discharging into a chute 14, which inturn discharges into the first groove of the mill through a circularaperture 15, in the head 16, of the grinding barrel. A light cover 15'supported by the chute 14, or in any other suitable manner, covers theaperture 15 in head 16. thus preventing the escape of dust through 15.

The lower end of the barrel is closed by a fixed housing 17, having acircular opening in which the end of the drum 1, rotates. The drum doesnot bear in the housing 17,

but should make a fairly close fit with the housing in order to preventdusting. The housing 17, also is provided with a manhole 18 whichfurnishes a means of access to the interior of the drum. An opening, 19.in the bottom of the housing permits of the ground material dischargingfrom the last groove 4, to enter the casing of the screw conveyer 20.

The fixed shaft 2, of the barrel is supported in bearings 21 and 21' inthe supports 22 and 22. A spur-wheel 23, keyed to the axial shaft 2,gears with the spur-wheel 24, carried by the shaft 25, of the hand-wheel26. Holes 28 are bored in the web of the spur-wheel 23, and on the wheel23 being rotated any one of the holes 28 may be caused to register witha hole 30. in the support 22. A pin 27 can be inserted through that oneof the holes 28, which register with 30, into the hole 30, in thesupport 22, thus locking .a driving shaft 34. Keyed to the shaft 34,

are the pulleys 35, corresponding to the loose pulleys 31 on shaft 2.Belts 36, work on the pulleys 31 and 35. These belts carry a number ofsemi-circular blades 37, set perpendicular to the belt and of a diametersomewhat smaller than that of the grooves 4. The driving shaft 34:, isset at such distance from the fixed axis 2, that when the belts are inposition on the pulleys 31 and 35,,the blades 37, project into theircorresponding grooves. Supported by the brackets 32, are small chutes38, one to each belt, which divert the material falling from the beltsinto the next groove toward the discharge end of the mill. The end ofthe shaft next to the feed end of the mill carries a spur-wheel 39. Thismeshes with an interior gear 40, carried by the head 16.

The method of operation of the mill is as follows: The motor beingstarted, and a rapid motion of rotation having been communicated to thegrinding barrel the material to be ground is fed into it through thechute 14, falling into the first groove ofcthe mill. .The rotation ofthe barrel carries the material under the first ball which, of course,rolls in the groove as the barrel is rotated, maintaining a position inthe lower part of the grinding drum 1, under the influence of gravity.The material in the grooves offers a certain resistance to the rollingof the balls, and, as a consequence, there is a lateral displacement ofthe balls from the middle position relative to a vertical plane throughthe axis of the mill which they occupy when at rest. The ball acts as aroller, more or less, crushing the material. The centrifugal forcedeveloped by the rotation causes the particles of the material, afterpassing under the first ball, to be carried up well into the upperquadrant of the path of rotation of the drum until the tangentialcomponent of the force of gravity has become sufficient to overbalancethe centrifugal force when the partially ground material falls away fromthe wall of the drum and tends to roll back into the lower quadrant.Instead of rolling back. however, it is intercepted by the blades orscoops on the belt of the first conveyer and carried by the belt to theother side of the axis of the drum.

and discharged into the first chute 38, which deflects the fallingmaterialinto the second groove 4, on the descending side of the drum.The continued rotation of the drum,

as before, carries the material under the ball of that groove, and intothe upper quadrant from where it falls onto the second belt, is againcarried to the other side of the axis and deflected into the thirdgroove. This action is repeated until the material now finely ground, isdischarged from the last of the chute 19, in housing 17. From 19, theground material falls into the conveyer 20, and is conveyed to storageor to screening apparatus. In the latter case, any material which isover the fineness required is returned to the feed conveyer 13, to bereground. With materials of different gravities, it is evident, thatwith the-same speed of rotation the materials will be carried todifferent heights before falling back to the lower part of the groove.To meet this condition, the fixed'shaft of the drum may be adjusted byoperating the hand-Wheel 26, as before explained, until the conveyerbelts 36, are in the proper position to take up the ma terial.

In the construction of my apparatus I prefer to use for the lining orgrinding surface 3, of the drum 1, segmental blocks of vitrified clay,as already explained, and to make the grinding balls of the samematerial. It 1s manifest, however, that if for any reason preferred,both the lining 3, of the drum and the balls themselves'may be of metal,or the lining, 3, may be made of either vitrified clay or metal and theballs of suitably dressed flint pebbles of large size. It is highlyadvantageousihowever, to use the sectional construction described. Witha sectional construction of the lining, any of the segmental blockswhich may be broken or Worn out during the operation of the mill, may beeasily removed and replaced with new blocks. With this construction, thelining may be maintained in good condition indefinitely by simplyrenewing small sections of the lining as they become worn with newblocks, and the necessity of entirely relining the drum on account oflocal wear avoided.

I have found that in the grinding of such materials as coke there is anexcessive wear on metal grinding surfaces. As the renewal of these partsof the grinding apparatus involves considerable expense when they aremade of metal,I prefer to use for them whenever possible, vitrifiedclay, as already mentioned. I have found that in the grinding of cokethis material gives excellent re sults and when not subjected to'impactor grinding contact wears well and costs far less for renewals thanmetal. It is not possible to use this substance in ball mills of theordinary type-because in these the balls are charged into the grindingdrum in a tween themselves and to blows from tumbling about in therevolving drum. When made of fireclay this causes a rapid wear anddisintegration of the grinding balls. In my present invention, however,this objectionable action is avoided by the fact that I do away with theviolent abrading action that takes place between the balls and byisolating them in separate grooves prevent any abrasive action betweenthe grinding surfaces. The balls simply roll in the grooves and are, forthe most, always separated from actual contact with the walls of thegrooves themselves by a thin layer of the material that is being ground.This is usually much softer than the vitrified clay of the grindingsurfaces, so that the wear on the latter is reduced to a minimum.

Having described my invention what I claim is:

1. In a grinding apparatus, the combination of a rotatable drum havingan interior grinding surface comprising circular corrugations, saidcorrugations being contiguous and the diametral planes of saidcorrugations being perpendicular to the axis of said rotatable drum,grinding balls in said circular corrugations, and a separate beltconveyer cooperating with each of said grooves for discharging groundmaterial from that groove.

2. In a grinding apparatus the combination of a rotatable drum, having aplurality of grinding surfaces arranged circumferentially on theinterior surface of said rotatable drum, a substantially sphericalgrinding body cooperating with each of said surfaces and adapted to makea rolling contact with the surface upon the rotation of said drum, aseparately rotatable conveying means cooperating with each of saidsurfaces and actuated by the rotation of said drum for removing fromthat surface substantially all of the material thereon which has passedunder the grinding body cooperating with that surface and fortransferring the said material to the adjacent grinding surface.

.3. In grinding apparatus the combinationof a substantially horizontalrotatable drum, having a plurality of continuous concave grindingsurfaces arranged circumferentially on the interior surface of saidrotatable drum, a grinding body cooperating with each of said surfacesand adapted to make a rolling contact with the surface, the thickness ofsaid grinding body being greater than the depth of the concavity of saidgrinding surfaces, an endless belt conveyer cooperating with each ofsaid grinding surfaces and adapted to remove from that surface andtransfer to the adjacent grinding surface the major portion of thematerial thereon which has passed under the grinding body cooperatingwith that surface, bearings for said drum, means for feeding thematerial to be ground to the first of said plurality of grindingsurfaces, means for discharging the ground material from the last ofsaid grinding surfaces and means for imparting rotation to said grindingdrum. substantially as described.

4:. In a grinding apparatus the combination of a rotatable grindingdrum, having a plurality of concave grinding surfaces arrangedcircumferentially on the interior surface of said rotatable drum, thesaid concave grinding surfaces having a semi-circular cross-section on aradial plane perpendicular to their diametral planes, a substantiallyspherical grinding ball cooperating with each of said concave grindingsurfaces and adapted to roll on said surfaces upon the rotation of saidgrinding drum, bearings for said drum, means for feeding the material tobe ground to the first of said grinding surfaces. means for preventingthe material from one surface. after it has passed under the grindingball cooperating with that surface, from again passing under said balland for transferring the said material to the next adjacent surfacetoward the discharge end of the drum, in a position to pass under thegrinding ball -cooperating with the said adjacent surface.

means for discharging the ground material from the last of saidplurality of grinding surfaces. and means to cause the rotation of saidgrinding drum, substantially as described.

5. In a grinding apparatus the combination of a rotatable circularlycorrugated grinding drum having an interior grinding surface, thediametral planes of the corrugations of said surface being substantiallyperpendicular to the axis of said rotatable drum and the cross-sectionof said corrugations on planes passing through the axis of said grindingdrum comprising substantially an arc of a circle, approximatelyspherical grinding bodies cooperating with each of said corrugations andadapted to make rolling contact with the surface of said corrugationsupon the rotation of said grinding drum, said grinding bodies being ofgreater diameter than the depth of said corrugations, bearings for saiddrum, an axial shaft extending through said drum.

but structurally independent of said drum.

means for removing from each corrugation and transferring to theadjacent corrug. tion the major portion of the material in thatcorrugation after said material has passed under the grinding bodycooperating with that corrugation. said means being supported by thesaid axial shaft. means for feeding the material to be ground to thefirst of said corrugations. means for discharging the ground materialfrom the last of said corrugations. and means for rotating said grindingdrum. substantially as described.

6. In a grinding apparatus the combination of a rotatable circularlycorrugated grinding drum having an interior grinding surface. a grindingball in each of the corrugations of said surface adapted to make arolling contact with the surface of the corrugations upon the rotationof said grinding drum. bearings for said drum, an axial shaft extendingthrough. said drum but structurally independent of said drum, supportsfor said shaft, means for fixing Said shaft in'a fixed position in saidsupports,

brackets on said shaft supporting a second shaft located eccentricallyin reference to said drum, pulleys on said axial shaftand on said secondshaft, belts working on the cooperating pulleys of the respective shaftsadapted to take up the material to be ground from one corrugation andtransfer it to the next adjacent corrugation toward the discharge end ofthe drum, means for feeding the material to be ground to the first ofsaid corrugations, means for discharging the ground material from thelast of said corrugations, and means for causing the rotation of saidgrinding drum, substantially as described.

7. A grinding mill comprising in combination a substantiallycylindrical, revoluble, drum, a lining for the shell of said drum, saidlining having a plurality of contiguous grooves. the cross-section ofeach of said grooves on a plane passing through the axis of said ,drumcomprising an arc of a circle in its middle portion. a plurality ofsubstantially spherical grinding balls, one of said halls being locatedin each of said grooves and adapted to roll freely. therein upon therotation of said drum, and a separately-rotatable conveying means foreach of said grooves for removing from said grooves the material thathas passed under the grinding balls of the respective grooves andtransferring said material to the next adjacent groove. in position topass under the grinding ball of said adjacent groove.

8. A grinding mill comprising in combination. a SllhStflTltlHllycylindrical shell, a lining for said shell. said lining having aplurality of contiguous circular corrugations. said corrugations forminga plurality of runs for grinding bodies, a plurality of substantiallyspherical grinding balls, one of said grinding balls being located ineach of said runs. and a plurality of scoops cooperating with each ofsaid runs, the said scoops being adapted to enterth e run With whichthey are cooperating on the ascending side of the drum and remove fromsaid run the major portion of the material therein which has passedunder the grinding ball therein.

0. A grinding mill comprising in combination, a substantiallycylindrical shell, a lining for said shell, said lining having circulargrooves around the inner periphery of the same, a substantiallyspherical grinding ball co-acting wlth each of said circular grooves, aplurality of scoops cooperating with each of said circular grooves, thesaid scoops being adapted to enter that groove with which they arecooperating and remove therefrom material therein which has passed underthe grinding ball inthat groove, and means for conducting the materialremoved from said scoops to the next adjacent groove toward thedischarge end of said drum.

10. grinding mill comprising in combination a substantially cylindricalshell, a lining for said shell, said lining having circular groovesaround the inner periphery of the same, a plurality of grinding balls,one of said grinding balls being adapted to roll in each of saidcircular grooves, an axial shaft extending through said grinding drumand having bearings without said drum, a plurality of scoops cooperatingwith each of said circular grooves, said scoops being supported in saiddrum by said axial shaft in such manner that said scoops will enter thegroove with which they are cooperating on the ascending side of the drumand remove from said groove the major portion of the material thereinwhich has passed under the grinding ball cooperating with that groove.

11. A grinding mill comprising in combination a substantiallycylindrical shell, a lining for said shell, said lining having circulargrooves around the inner periphery of the same, a substantiallyspherical grinding ball coooperating with each of said circular grooves,an axial shaft extending through said grinding dnum and having bearingswithout said drum. means for fixing said axial shaft in said bearings, aplurality of brackets fixed to said axial shaft, a driving shaftsupported by said brackets, a plurality of scoops cooperating with eachof said circular grooves, said scoops being actuated by said drivingshaft and adapted to enter the groove with which they are cooperatingand remove from said groove the major portion of the material thereinwhich has passed under the grinding ball in that groove.

12. A grinding mill comprising in comblnation an outer shell, a hiringfor said ,shell, said lining having a plurality of circular groovesaround the inner peripheryof the same, a plurality of grinding balls,one of said grinding balls co-acting with each of said circular grooves,an axial shaft extending through said grinding drum and having bearingswithout said drum, means for clamping said shaft in a fixed position,,

a plurality of scoops mounted on each of said belts, the said beltsbeing supported in such manner that the scoops of each belt willsuccessively enter the groove with which they are cooperating and removefrom that groove the ma]or portion of the material thereon which haspassed under the grinding ball co-acting with that groove.

13. A grinding mill comprising in combination a substantiallycylindrical drum, a head closing one end of said drum and attached tosaid drum and a fixed housing closing the other end of said drum, alining for said drum, said lining having a plurality of circular groovesaround the inner periphery of the same, a plurality of grinding balls,one of said grinding balls coaeting with each of said circular grooves,an axial shaft extending through said grinding drum and having bearingswithout said drum, means for fastening said shaft in a fixed position, aplurality of brackets fixed to said axial shaft, a driving shaftsupported by said brackets, a plurality of endless belts, one of saidbelts eo-acting with each of said grooves, said belts being supported bysaid shafts and actuated by said driving shaft, a plurality of scoopsmounted on each of said belts, the said belts being supported in suchmanner that the scoops of each belt will successively enter the groovewith which they are cooperating and remove from said groove the majorportion of the material therein which has passed under the grinding ballcooperating with that groove.

14. A grinding mill comprising in combination a substantially horizontalgrinding drum having an interior circularly grooved grinding surface andgrinding balls in the grooves of said surface, and means for conveyingmaterial from groove to groove of said surface, said conveying meanscomprising an axial shaft extending through said grinding drum andhaving bearings with-- out said drum, means for fastening said shaft ina desired fixed position, a plurality of brackets fixed to said axialshaft, a driv- I ing ball cooperating with that groove, a plurality ofchutes, one of said chutes co-acting with each of said belts to receivethe material removed by said belt and conduct the said material into thegroove adjacent to the groove with which the said belt is co-acting.

15. The combination of a grinding drum having a peripherally groovedinterior grinding surface and a grinding ball in each of the grooves ofsaid surface, and convey ing means co-acting with each groove of saidgrinding surface and adapted to move material from groove to groove.said conveying means comprising an axial shaft extending through saiddrum but structurally independent thereof, supports for said axialshaft, means for clamping said axial shaft in a selected fixed position,a plurality of brackets fixed to said axial shaft, a plurality ofindividual conveyers, one of said conveyers cooperating with each ofsaid grooves and being adapted to transfer material from that groove tothe next adjacent groove toward the discharge end of said drum, saidindividual conveyers being supported from said axial shaft and beingadjustable in position by rotating said axial shaft, a driving shaftsupported by said brackets, said driving shaft being substantiallyparallel to said axial shaft and adapted to drive said individualconveyers.

16. A. grinding mill comprising an outer drum of substantially circularcross-section, a lining for said drum, said lining having a plurality ofcontiguous circular grooves, a plurality of grinding balls adapted toroll in said circular grooves, and conveying means cooperating with saidgrinding drum, said conveying means comprising a shaft mounted axiallywithin said drum. means independent of said drum for varying the angularposition of said shaft, a driving shaft substantially parallel to saidaxial shaft and supported within saiddrum. a plurality of conveyerssupported by said shafts and adapted to cooperate with said grooves tomove material from groove to groove, said conveyers each comprising aloose-pulley mounted on said axial shaft, a tight-pulley in alinementwith said loose pulley mounted on said driving shaft and conveyermembers operated by said pulleys.

Signed at New York city in the county of New York and State of New York,this 28th day of October, A. D. 1909.

HENRY i l. DUHERTY.

Witnesses THos. I. CARTER, C. B. GILBERT.

@opies of this patent may be obtained for five cents eacmhy addressingthe "Commissioner of Patents, Washington, D. G.

